The question as to how action research (AR) is related to cultural-historical activity theory (CHAT) is not answerable in categorical terms. Both CHAT and AR have been variously interpreted and much depends on the individual biographies of those who pronounce on their relationship. The aim of this paper is to show how action research, conducted collaboratively, can enact principles for learning-and-teaching derived from CHAT and how, at the same time, AR can contribute to the development of CHAT. The author has tried to support these claims by providing an account of his own development as a researcher, learner and teacher. (Contains 8 footnotes.)